Shifting Precipitation Patterns Drive Growth Variability and Drought Resilience of European Atlas Cedar Plantations

Jesús Julio Camarero,Fernando Silla,François Courbet,Rafael M. Navarro-Cerrillo,Álvaro Rubio-Cuadrado,Antonio Gazol,Michele Colangelo,Juan Carlos Linares,Pierre-Jean Dumas

doi:10.3390/f12121751

Abstract

Tree plantations have been proposed as suitable carbon sinks to mitigate climate change. Drought may reduce their carbon uptake, increasing their vulnerability to stress and affecting their growth recovery and resilience. We investigated the recent growth rates and responses to the climate and drought in eight Atlas cedar (Cedrus atlantica) plantations located along a wide climate gradient from wetter sites in south-eastern France and north Spain to dry sites in south-eastern Spain. The cedar growth increased in response to the elevated precipitation from the prior winter to the current summer, but the influence of winter precipitation on growth gained importance in the driest sites. The growth responsiveness to climate and drought peaked in those dry sites, but the growth resilience did not show a similar gradient. The Atlas cedar growth was driven by the total precipitation during the hydrological year and this association strengthened from the 1980s onwards, a pattern related to the winter North Atlantic Oscillation (NAO). High winter NAO indices and drier conditions were associated with lower growth. At the individual level, growth resilience was related to tree age, while growth recovery and year-to-year growth variability covaried. Plantations’ resilience to drought depends on both climate and tree-level features.

Highlights

Climate models forecast harsher conditions for many conifer forests due to a higher recurrence of extreme climatic events such as droughts, which will negatively impact their productivity, reducing tree growth and constraining growth resilience [1,2]
The growth of Atlas cedar plantations from drought-prone areas in south-western Europe was sensitive to water shortage, from the prior winter to the current spring, but with strong variations from site to site
The growth of plantations from the wettest sites in south-eastern France and northern Spain were more related to spring and summer precipitation and it appears slightly constrained by shorter drought periods

Summary

Introduction

Climate models forecast harsher conditions for many conifer forests due to a higher recurrence of extreme climatic events such as droughts, which will negatively impact their productivity, reducing tree growth and constraining growth resilience [1,2]. If droughts become more severe and frequent, recurrent stressing conditions may reduce their long-term growth recovery [3], worsening forest health and rising mortality rates [4,5]. A reduced post-drought growth recovery leads to a declining resilience due to drought legacies or carryover effects, which challenge the ability of forests to act as effective carbon sinks, limiting their potential to mitigate climate warming [6,7]. Reliable field assessments of growth resilience across wide climatic gradients are needed to quantify the role played by conifer plantations in climate change mitigation

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